Naidenov, Georgi, and Kaloyan Haralampiev. “Local and Global Risk Factors for the Development of Bulgaria and the World in the Second Decade of the 21st Century”. UNWE Yearbook, no. 1 (January 27, 2016): 49–98. Accessed July 22, 2026. https://bjiep.e-dnrs.org/index.php/yb/article/view/5999.